Observations on the nature and theory of vision : with an inquiry into the cause of the single appearance of objects seen by both eyes / by John Crisp, F.R.S.
- Crisp, John
- Date:
- MDCCXCVI [1796]
Licence: Public Domain Mark
Credit: Observations on the nature and theory of vision : with an inquiry into the cause of the single appearance of objects seen by both eyes / by John Crisp, F.R.S. Source: Wellcome Collection.
Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.
173/206 page 151
![[ 15' ] this, that when the left eye was uncovered, the fpace O P of the right axis, which was before invifible to the right eye, now became an objed: of fight interpofed be^ tween O and P, fimilar to the fide of the cube. And upon the fame principles is to be ex- plained the reafon why, in different real pofi- tions of the optic axes an objed: fituated in them may appear to have but one and the fame direction. For, when the eyes are fuc- cefiively directed to different points, all lying- in a line perpendicular to, and bifefting, the vifual bafe, it is evident, that while both eyes are ufed, the field of vifion will in each cafe be divided by the fame plane; for, notwith- ftanding the extent of the field, or the range of fight, is contrad:ed as the eyes arc directed to the more remote points, and the axes ap- proach to parallelifm, yet the contraftion being equal on the right and on the left fide, the plane of divifion muft, throughout^ re-](https://iiif.wellcomecollection.org/image/b21175408_0173.jp2/full/800%2C/0/default.jpg)
